This invention relates to an arrangement for fuel supply to the combustion chambers of a vehicle internal combustion engine with an engine braking disconnection. More particularly, the invention relates to a fuel supply arrangement that supplies fuel to all, less than all, or none of an engine's combustion chambers based on engine speed and load.
The invention is an improvement in the fuel supply arrangements known from:
Offenlegungsschrift No. 22 55 350 PA1 Offenlegungsschrift No. 26 12 172 PA1 Offenlegungsschrift No. 27 24 487
The arrangement known from Offenlegungsschrift No. 22 55 350 contains two devices which operate separately, although the two devices are structurally connected. One device causes a reduction in the fuel supply, and finally an elimination of the fuel supply, to fuel injection nozzles following the return of the accelerator pedal to its rest position. The second device is controlled by a microswitch located near the accelerator pedal which elminates the fuel supply to individual combustion chambers or groups of combustion chambers during idling and operation of the engine under small engine loads.
In view of its division into the above described two devices, this arrangement is complex in construction. Additionally, this arrangement suffers from the disadvantage that the elimination of the fuel supply to individual combustion chambers or groups of combustion chambers, and thus the corresponding resumption of the fuel supply to the chambers, occurs independent of the prevailing rotational speed of the engine, and, rather, at a constant accelerator pedal position, which, due to the arrangement of the microswitch, is fixed in advance. For the above reasons, the arrangement does not operate at optimal consumption conditions. Another disadvantage of this arrangement is the occurence of an undesirable power jump, or "starting jerk," when the fuel supply is connected to or disconnected from the individual combustion chambers or groups of combustion chambers.
To this end, Offenlegungsschrift No. 26 12 172 discloses an improvement in the fuel supply arrangement designed to alleviate this undesirble power jump by providing for the actuation of the intake manifold throttle valve during the connecting/disconnecting operation. However, the coupling between a swivel segment connected on the one hand to the accelerator pedal, and on the other hand to the throttle valve shaft is accomplished in such a manner that the driver is able to operate the vehicle such that defined operating points in the power-rotational speed diagram are attained that are not optimal insofar as fuel consumption is concerned. Additionally, this arrangement does not mention an engine braking disconnecting feature as does the present invention, nor is an engine-braking feature disclosed in the Offenlegungsschrift No. 27 24 487.
In the Offenlegungsschrift No. 27 24 487, the elimination of the fuel supply to individual combustion chambers or groups of combustion chambers occurs as a function of signals received from comparators. The comparators receive signals from function generators which are connected with a rotational speed sensor and compare these signals with a load signal, the load signal being a function of the negative pressure in the intake manifold of the engine. In this case it is possible to provide rotational speed-dependent transitions between engine operation with all combustion chambers, or with only individual or groups of combustion chambers, in accordance with the several operating ranges in the power vs. rotational speed diagram of the engine, but the load signal is not itself independent of the rotational speed.